1. Field of the Invention
This invention generally relates to bicycles, and more particularly to a self-stabilizing device including training wheels for stabilizing the bicycle when tilting while making turns.
2. Description of the Prior Art
Conventional training wheel assemblies typically consist of rigid brackets which are mounted onto the rear axle of a bicycle. One such construction is shown in U.S. Pat. No. 4,615,535. However, such brackets have very little give since they are normally formed of thick steel bars. During a sharp turn, when the bicycle tilts significantly into the turn, the bicycle weight is transferred from the main rear wheel to the training wheel on the side on which the bicycle tilts. Where the bicycle tilts excessively, and the center of gravity extends beyond the respective training wheel, restoring the balance against the centrifugal force becomes very difficult if not impossible, this resulting in an increased risk of falling.
A number of attempts have been made to provide a more flexible training wheel arrangement which can accommodate changes in the tilting positions of the bicycle. Most of these proposed training wheel constructions have generally been cumbersome, complex and expensive to manufacture. Typical of such constructions are the devices disclosed in U.S. Pat. Nos. 720,860; 1,077,210; 1,576,133; and 1,601,392. The aforementioned patents typically involve numerous combinations of articulated arms, springs and other components.
In U.S. Pat. No. 590,568, a self-balancing bicycle attachment is disclosed which includes a bifurcated arm in which there is formed a pocket or recess for receiving a spring which cooperates with a screw mounted on a lug formed on a supporting arm sharing a common pivot with the bifurcated arm. The training wheel is mounted on the bifurcated arm. The spring permits the bicycle to be yieldingly supported when in motion to conform to various inclinations of the surface over which the bicycle moves. However, the bifurcated arm and the supporting arm are also connected by means of a tension spring which prevents the bifurcated arm from swinging excessively downward as the bicycle is raised on one side. With excessive tilting, therefore, the training wheel is forced upwardly and raised above the ground. A similar problem is exhibited in U.S. Pat. No. 2,450,979 for an attachment to bicycles which is intended to afford lateral stability. However, the fixed or rigid bracket attached on each side of the bicycle includes an upwardly open vertical slot which receives a spindle on which the training wheel is mounted. While the tilting of the bicycle in one direction allows a spindle on that side to move upwardly within the open slot, the corresponding motion prevents the spindle on the other side moving below the bottom of the open slot. This causes the spindle and the training wheel mounted on it to be raised. For sharper turns involving any degree of tilt, the training wheel is raised above the ground. A further construction which shares this similar problem is disclosed in U.S. Pat. No. 4,595,213 for an auxillary wheel arrangement for use on bicycles. Here, the arms on which the training wheel are mounted are confined within U-shaped guide frames which prevent the arms from being lowered beyond a predetermined point. Again, therefore, with excessive tilt, the wheel on the side opposite to the tilting direction is raised above the ground.
In U.S. Pat. No. 4,810,000, a compensating training wheel assembly for a bicycle is disclosed which includes generally rigid brackets attached on each side of the rear wheel of the bicycle. A link member is attached to the lower end of each bracket on which the training wheels are mounted. The link members are controlled by a system of cables connected to clamps mounted via tubular portions forming the front fork of the bicycle. Such arrangement pivots the auxillary wheels between the raised and lowered conditions in response to a steering turn of the front wheel. However, this construction is somewhat complicated and cumbersome to install. Additionally, since the positions of the training wheels are only a function of the position of the steering wheel, and do not in any way depend on the tilt or orientation of the bicycle itself, the swerving of the handle bars by an inexperienced bicycle rider could destabilize the bicycle instead of promoting stability.